Low-cost water filter alerts users when water is safe to drink

Turning contaminated water into clean drinkable water can be as easy as filling clear plastic PET bottles with the source water and exposing them to direct sunlight until the UV rays disinfect the water.

It's simple, it's cheap, and it's effective for areas without access to clean water or advanced water purification devices.

But it's not easy to determine exactly when the water is disinfected, which means that people may end up drinking water that isn't fully disinfected, or waiting longer than they need to in order to get potable water. For instance, in some areas with intense sunlight (and in certain times of the year), the disinfection with SODIS can take as little as 45 minutes, and in other areas and times of the year, the process can take up to 2 days.

However, a new low-cost device may make that process much simpler, by measuring the UV radiation hitting the bottle and determining how long the water needs to be in the sun and letting users know when the water is ready to drink.

WADI, from an Australian startup called Helioz, is a solar-powered portable gadget that can turn the length of the solar disinfection (SODIS) process from a "best guess" to an exact time, which could make a huge difference in the lives of people who depend on the SODIS process for their potable water needs.

"WADI contains a UV sensor that measures the sun’s UV radiation and then compares the measurements with scientifically proven reduction of pathogens in the water. The synergetic processes of UV-induced inactivation (dose- and time-dependent) are integrated with opposing processes stemming from the repair mechanisms of the pathogens. Even during difficult weather conditions (e.g. low light conditions, clouds and/or rain), WADI reliably indicates an optimized exposure time for the necessary reduction of the pathogens. By means of a happy smiley face, WADI lets its user know as soon as the water has reached a bacterially and virally safe drinking water status (4 log-levels/99.99%)." - Helioz

"With its built-in solar cell, WADI is energy-self-sufficient, affordable and has a guaranteed life time of at least two years. The device can be used and shared by several persons and families since many bottles of water can be purified simultaneously. Internationally understandable pictograms on the device facilitate correct usage. WADI is not only meant to be a life-saving tool which satisfies basic human needs but also a lifestyle product which brings easy and inexpensive solar water disinfection to remote low-income households." - Helioz

Right now, Helioz is running a crowdfunding campaign on Indiegogo for the WADI device, which will allow the company to conduct a scientific health impact study in Odisha, India (an area with the third highest under-5 mortality rate in India), in order to be able to better meet the specific needs of people in areas that are affected most by waterborne diseases.

According to the company, the WADI will be available by sometime in January 2014, and the cost will be set at different prices, depending on both the specific markets and customer segments they are sold to, in order to be an affordable and viable water safety device.